Power control apparatus and power control method of construction machine

Abstract

The present disclosure provides a power control apparatus of a construction machine, including: an engine connected to a hydraulic pump to drive the hydraulic pump; and a controller for calculating an engine load ratio defined as a ratio of a load torque of the engine for an engine maximum torque calculated from an input engine target RPM, and calculating an engine RPM command value according to the engine load ratio such that the engine is driven at the target RPM to output the calculated engine load ratio and engine RPM command value to the engine.

The invention claimed is: 
     
       1. The power control apparatus of a construction machine, comprising:
 an engine connected to a hydraulic pump to drive the hydraulic pump; and 
 a controller for calculating an engine load ratio defined as a ratio of a load torque of the engine to an engine maximum torque, the engine maximum torque calculated from an input engine target RPM, and the controller calculating an engine RPM command value according to the engine load ratio such that the engine is driven at the target RPM to output the calculated engine load ratio and engine RPM command value to the engine, 
 wherein the controller includes: 
 an engine control unit for calculating the engine maximum torque from the engine target RPM, calculating the engine load torque from a fuel injection amount command value output to the engine, and calculating the engine load ratio from the calculated engine maximum torque and engine load torque to output the calculated engine maximum torque, engine load torque, and engine load ratio; and 
 an equipment control unit for calculating the engine RPM command value from the engine load ratio output from the engine control unit to output the calculated engine RPM command value to the engine control unit, and wherein the engine control unit calculates the fuel injection amount command value according to the engine RPM command value transmitted from the equipment control unit to output the fuel injection amount command value to the engine. 
 
     
     
       2. The power control apparatus of  claim 1 , further comprising:
 a horse power regulating unit for varying a swash plate angle of the hydraulic pump to vary a required horse power of the hydraulic pump; and 
 a pressure sensor for detecting a load pressure of a working fluid discharged from the hydraulic pump, 
 wherein the equipment control unit calculates a target pump requiring horse power from the load pressure detected by the pressure sensor, and controls the horse power regulating unit such that a required horse power of the hydraulic pump gradually approaches the target pump requiring horse power for a preset time. 
 
     
     
       3. The power control apparatus of  claim 2 , wherein when the load pressure detected by the pressure sensor is a non-load pressure, the target pump requiring horse power is set to a minimum horse power, if the load pressure detected by the pressure sensor is a maximum set pressure, the target pump requiring horse power is set to a maximum horse power, and the maximum set pressure is set to be lower than or equal to a pressure of a constant horse power control starting point of a maximum horse power of the hydraulic pump. 
     
     
       4. The power control apparatus of  claim 2 , wherein the horse power regulating unit includes:
 a horse power regulating part for regulating the swash plate angle of the hydraulic pump according to the pilot pressure input from the pilot pump; and 
 an electronic proportional pressure reduction valve for varying an opening degree of a passage connecting the pilot valve and the horse power regulating part according to a magnitude of a current command value input from the equipment control unit. 
 
     
     
       5. A power control apparatus of a construction machine for controlling a hydraulic pump driven by an engine, comprising:
 a horse power regulating unit for varying a swash plate angle of the hydraulic pump to vary a required horse power of the hydraulic pump; 
 a pressure sensor for detecting a load pressure of a working fluid discharged from the hydraulic pump; and 
 a controller for calculating a target pump requiring horse power from the load pressure detected by the pressure sensor, and controlling a horse power regulating unit such that a required horse power of the hydraulic pump gradually approaches the target pump requiring horse power for a preset time, 
 wherein when the load pressure detected by the pressure sensor is a non-load pressure, the target pump requiring horse power is set to a maximum horse power, if the load pressure detected by the pressure sensor is a maximum set pressure, the target pump requiring horse power is set to a maximum horse power, and the maximum set pressure is lower than or equal to a pressure of a constant horse power control starting point of the maximum horse power of the hydraulic pump, 
 wherein the preset time Δt is proportional to a horse power difference value between a current pump requiring horse power of the hydraulic pump and the target pump requiring horse power. 
 
     
     
       6. The power control apparatus of  claim 5 , wherein the horse power regulating unit includes:
 a horse power regulating part for regulating the swash plate angle of the hydraulic pump according to the pilot pressure input from the pilot pump; and 
 an electronic proportional pressure reduction valve for varying an opening degree of a passage connecting the pilot valve and the horse power regulating part according to a magnitude of a current command value input from the controller.